Photographic printer



July 10, 1962 H. R. BENSON 3,043,204

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United States Patent 3,043,204 PHOTOGRAPHIC PRINTER Harold R. Benson,Lombard, Ill., assignor to The Nuarc Company, Chicago, 11]., acorporation of Illinois Filed Mar. 10, 1959, Ser. No. 798,522 Claims.(CI. 9576) The present invention relates to photographic printers, and,more particularly, it relates to contact printing apparatus useful inexposing the sensitized metallic plates in a process for photoengravingoifset plates.

In order to photoengrave a metallic plate so that it may be usedthereafter to reproduce a work of art or the like, aphotographicnegative is first made of the work to be reproduced andthereafter a sensitized metal plate is selectively exposed to thepattern of light corresponding to the work of art by interposing thenegative between the sensitized surface of the plate and a source oflight. Following the exposure of the plate in this manner, thesensitized surface is subjected to an acid etchant which selectivelyremoves the unexposed portions of the sensitized surface thereby toprovide what is commonly referred to as an offset printing plate, thesurface of the plate having hills and valleys corresponding to the Workof art being copied.

An object of the present invention is to provide new and improvedapparatus useful in selectively exposing sensitized metal plates in thephotoengraving thereof.

Another object of the present invention is to provide a new and improvedcontact printer for selectively ex- .posing sensitized metal plates.

A further object of the present invention is to provide a new andimproved photographic printer which is easy .to use and which insuresthat the sensitized plates are axis thereof. Because it is mounted inthis manner the frame can be pivoted to one position in which theloading side thereof is toward the light source and in a second positionwherein the loading side of the printing frame is 'toward the top of thecabinet away from the light source.

Accordingly, the plate and the negative may be loaded .into the framefrom the top side thereof and the frame may then be pivoted into theposition wherein the plate is exposed to the light source.

Further objects and advantages of the present invention will-becomeapparent as the following description proceeds, and the features of thenovelty which characterize the invention will be pointed out withparticularity in the claims annexed to and forming a part of thisspecification.

For a better understanding of the present invention,

reference may be had to the accompanying drawings in I which:

FIGfl is a front elevational view of a photographic contact printerembodying the present invention;

FIG. 2 is another front elevational view of the printer of FIG. 1showing the printing frame thereof in a different position;

FIG. 3 is a sectional view taken along the line 3 3 of FIG. 4 is asectional view taken along the'line 4-4 of FIG. 1;

3,043,204 Patented July 10, 1962 FIG. 5 is an enlarged fragmentarysectional view taken along the line 5--5 of FIG. 1;

FIG. 6 is a sectional view taken along the line 66 of FIG. 3 assumingthe entire structure to be shown therein;

FIG. 7 is a fragmentary sectional view, greatly enlarged, taken alongthe line 7-7 of FIG. 6 assuming that FIG. 6 shows the completestructure;

FIG. 8 is an enlarged fragmentary sectional view taken along the line 88of FIG. 6 assuming FIG. 6 shows the complete structure;

FIG. 9 is a sectional view somewhat enlarged and taken along the line9-9 of FIG. 4;

FIG. 10 is a sectional view somewhat enlarged and taken along the line10-10 of FIG. 4;

FIG. 11 is an enlarged end view of the upper portion of the printershown in FIG. 1 with certain portions thereof removed;

FIG. 12 is an enlarged sectional view taken along the line 12-12 of FIG.11 assuming the entire device to be shown therein;

FIG. 13 is a sectional view of the peripheral portion of a vacuumblanket embodying certain aspects of the present invention and used inthe printer of FIG. 1;

FIG. 14 is a perspective view of a fragmentary portion of a vacuumblanket embodying certain aspects of the present invention; and

FIG. 15 is a fragmentary cross sectional view of a portion of a printingframe embodying certain aspects of the present invention and used in theprinter of FIG. 1.

Briefly, and as best shown in FIGS. 1, 3, and.4 of the drawings, thereis provided in accordance with the pres- ,ent invention a photographicprinter 20 comprising a generally rectangular cabinet 21 having anautomatically operated carbon are light source 22 mounted in the bottomof the cabinet 21. Although in some embodiments of the present inventionthe carbon are light source may be suitably supported Within the cabinet21 in a relatively fixed manner, in the illustrated embodiment thislight source is mounted on a pull-out drawer 23. Also included in thecabinet is a generally parabolic reflector 24 including a pyramid-likemember for directing the light from the source 22 in a beam of uniformintensity throughout a predetermined area toward a printing frame 25pivotally mounted about a central axis thereof to the top of the cabinet21. The bottom of the frame 25, as shown in FIG. 1, comprises a-loadingstation and the top of the frame 25, as shown in FIG. 1, comprises animperforate protective cover. Accordingly, in order to place asensitized plate and negative in the frame 25 for exposure by the lightfrom the light source 22, the frame 25 is pivoted as shown in FIG. 2through degrees so that the loading station is at the top and theprotective cover is at the bottom. The frame 25 may then be loaded fromthe top, and after this has been done it is again rotated through 180degrees so that the loading station again faces toward the light source22. Following this, the light source 22 is energized for a predeterminedperiod of time to properly expose the sensitized plate with a lightpattern corresponding to the light and darkareas of the negative beingcopied. Upon completion of the exposure operation, the light source 22is deenergized and the printing frame 25 is rotated through 180 degreesto permit removal therefrom of the exposed plate and negative.

Where the drawer 23 is provided it will be apparent, that whenever itbecomes necessary to change the carbon electrodes of the light source 22or to remove the ash which collects therein during operation of theprinter the drawer 23 may be withdrawn from the cabinet 25. In this way,maintenance of the printer 20 and particularly the light source 22 is avery simple, fast and clean 1 operation.

The cabinet 21 may have a variety of constructions and in theillustrated embodiment is suitably constructed of sheet metal comprisinga relatively short bottom portion 31 and a taller top portion 32 whichis separate from the bottom portion 21 and is held in place thereon bymeans of a depending peripheral flange 33 which is suitably welded tothe upper cabinet part 32. As shown best in FIG. 4, the lower cabinetportion 31 houses the carbon are light source assembly 22, the reflector24, and a plurality of other control components including a motor drivenvacuum pump 34 and a power transformer 35. In other embodiments, thecabinet may be of one-piece construction with doors affording access tothe reflector, pump, etc.

The carbon are light source 22 is preferably of the type disclosed inPatent 2,774,907--Benson which is assigned to the same assignee as thepresent application, and a detailed description of it is given in thatpatent. However, for the purpose of understanding the present inventiona brief description thereof is suflicient. As shown best in FIGS. 3, 4,and 10, the light source 22 comprises a pair of electrode supports 36and 37 which are respectively mounted on a pair of racks 38 and 39. Theracks 38 and 39 are movable toward and away from one another and aresuitably driven by a control solenoid and spring mechanism (not shown)housed in a control box 4% for automatically maintaining a pair ofcarbon electrodes 41 and 42 which are mounted in the supports 36 and 37at the necessary distance apart to provide a uniform predeterminedintensity of light. As best shown in FIG. 10, the movable parts of thelight source 22 are mounted on top of the control box 45) which in theillustrated embodiment involving the drawer 23 in turn is suitablysecured to a supporting plate 44 having a pair of depending guideflanges 45 (FIG. received in a pair of guide channels 46 and 47. Thechannels 46 and 47 are respectively mounted on a pair of supportingchannels 48 and 49 which are fixedly mounted near the bottom of thelower cabinet portion 31 and extend from front to back thereof. Thefront of the drawer 23 comprises a face plate 51 which is suitablysecured as by Welding to the front end of the plate 44, and inasmuch asa toe space is provided along the bottom of the cabinet 21, the face ofthe drawer 23 is undercut and a second face plate 52 is secured to thebottom of the plate 44 and depends therefrom to cover the undercut faceportion of the drawer 23. An angulated handle 53 is secured to the faceplate 51 to facilitate opening of the drawer 23.

During operation of the carbon are light source 22, a certain amount ofash is produced, and in the illustrated construction the ash collects ina tray 56 which is located directly below the electrodes 41 and 42.Therefore, in order to facilitate removal of this ash from thereflector, the tray 56, which constitutes the lower central portion ofthe reflector 24 and which is best shown in FIG. 10, is suitably securedby means of an attachment assembly 57 to the top of the control box 40and is thus slidably connected to the remaining peripheral portion ofthe reflector 24, designated 58. Consequently, when the drawer 23 iswithdrawn from the cabinet 21, the tray 56 at the lower central portionof the reflector 24 is withdrawn and any ash which has been depositedthereon may be readily removed.

In order uniformly to direct the light from the arc, which is positionedbetween the tips of the electrodes 41 and 42, onto the printing frame25, the reflector 24, which is square when veiwed in plan, has asubstantially parabolic cross sectional configuration as best shown inFIG. 9 of the drawings. For the illustrated embodiment, the upper partof the reflector 24 is formed of a plurality of flat strips 61 which areeach so oriented that light rays from the are which strike the inneredge thereof are directed to a location slightly displaced from thecenter of the printing frame while light rays from the are which strikethe outer edges of the strips 61 are directed to the outer edges of theprinting frame. The upper ones of the strips 61 are off-turned at theupper edges thereof to provide a plurality of mounting flanges 62 whichare secured by suitable fastening means such as bolts 63 to a pluralityof channel supporting members 64 which are secured to inwardly directedperipheral flanges 65 at the top of the lower cabinet portion 31.Accordingly, the upper portion of the reflector 24 is fixedly mounted inthe bottom of the cabinet. It includes a pair of elongated slots 66 and67, best shown in FIGS. 3 and 4, to permit passage of the electrodeholders 36 and 37 through the lower portions of the reflector 24 as thedrawer 23 is withdrawn and to accommodate the electrode holders 36 and37 when they are most widely spaced apart at the time that new carbonelectrodes 41 and 42 are supported therein.

As can best be seen in FIG. 4, the tray 56 is substantially square inplan being formed of a pair of triangular plates 71 and 72 which, asbest shown in FIG. 10, are sandwiched between a pair of connector parts57a and 5712 together to compress the plates 71 and 72 therebetween, andthe part 5711 is fixedly connected by suitable means to the top of thecontrol box 46. Since the arc is not a point source of light, thereflector 24 must be designed to compensate for the peculiar shape ofthe arc. Consequently, the diagonal formed by the central surfaceportions 71a and 72a of the tray 56 is blackened as by carbonizing toprovide a substantially nonreflecting surface.

The bottom cabinet portion 31 of the illustrated embodiment furtherincludes a plurality of access doors 68, 69, and which facilitatemaintenance of the vacuum pump and associated motor 34 and thetransformer 35.

The upper cabinet portion 3.2 is a bottomless rectangular membersuitably formed of sheet metal and has an inwardly directed peripheralflange 75 at the bottom thereof which rests on the flange 65 of thebottom portion 31, and it further includes an inwardly directedperipheral flange 76 at the top thereof on which the printing frame 25is mounted. As best shown in FIGS. 1, 3, and 6, the printing frame 25 isrelatively thin and substantially rectangular in construction, includingas its principal structural element a somewhat cup-shaped member 78having a flat bottom portion 79 and four side walls 86 to the upper endsof which an imperforate, sheet metal cover 81 is attached: Since thecover 81 is preferably a stamping, a plurality of channel-shapedrigidifying ribs 82 are welded to the inner face thereof. The printingframe will have various sizes depending upon the particular application.

The printing frame 25 is pivotally mounted by means of a pair of pintles83 and 84 journaled in a pair of bearings 112 which are mounted on theflange 76. The pintles 33 and 84 are coaxially mounted along a centralaxis of the frame 25 so that the opening in the top of the cabinet 21 iscompletely covered by the frame 25 in either of two positions, i.e., aloading or an exposure position.

Referring to FIG. 11, a glass frame assembly 85, which includes a plateglass pane 86, is in the illustrated embodiment of the inventionpivotally attached to the rear side of the frame 25 by means of aplurality of hinges 87 which are suitably secured to the rear wall ofthe member 78 and to the glass frame assembly 85. As indicatedhereinbefore, during the loading operation, the frame 25 is inverted tothe position shown in FIG. 11 and in order to place the negative and thesensitized plate in the frame, the glass frame 85 is pivoted upwardly tothe position shown in phantom in FIG. 11. In other embodiments of thepresent invention, where a very large printing frame is employed, theglass frame 85 instead of being pivotally supported may bodily be raisedand lowered while disposed in a horizontal plane.

For the purpose of facilitating the lifting of the glass frame assembly85 into the position shown in FIG. 11, and to automatically retain it inthat position while the frame is being loaded, there is provided inaccordance with the present invention a spring lift assembly. Itcomprises as its principal components a plurality of lift arms 90 whichare respectively located at the side edges of the printing frame 85 andwhich respectively include a guide roller 91 which rides in a trackformed in guide channels 92 suitably secured to the respective edges ofthe frame 85. One end of a helical tension spring 93 is secured by abracket 94.to a point in the arm 90 in close proximity to the roller 91and the other end of the spring 93 is secured to the portion of thehinge 87 which is secured to the glass frame 85. In addition, the end ofthe arm 90 whichis remote from the roller 91 is pivotally secured to thecup-shaped member 78 by means of a pintle 95. Considering the operationof the spring lift assembly very briefly, with the glass frame 85 in thedown position, the springs 93 are stretched, and inasmuch as both endsthereof are below the pivotal axis of the hinges 87, the spring 93exerts a downward force on the glass frame 85 to keep it closed.Neverthe-- less in order to further insure that the frame 85 does .areraised above the pivotal axis of the hinges 87, the

springs 93 exert an upward force on the glass frame 85 and thus aid inlifting it. A pair of stops 98 are respectively provided in the guidechannels 92 for engaging the rollers 91 when the glass frame 85 is inthe phantom position shown in FIG. 11 thereby to permit loading of theprinting frame 25. When the glass frame 85 is in this position, thespring 93 is slightly stretched so as to exert a counterclockwise torqueon the arm 90 as viewed in FIG. 11 and thus hold the glass frame 85 inthe elevated position.

With the glass-frame 85 in the elevated position, the glass plateengaging surface of a resilient vacuum blanket 101, which rests on theface of the bottom 79 of the member 78, is exposed and a sensitizedplate may be placed thereon. The blanket 101 is preferably a onepiecemolding of rubber and, as best shown in FIG. 14, has a plate engagingface which comprises a plurality of square, truncated pyramids orprotuberances 102. As best shown in FIGS. 3, 6, 7 and 13, the blanket101 further includes a peripheral sealing portion 103 for engaging theglass 86 when the glass frame 85 is in a latched position thereby tohermetically seal the cavity defined by the glass pane 86 and theblanket 101. The seal 1103 consists of a generally arcuate bead which iscompressed into a generally tubular shape when the glass frame 85 is ina latched position. Since the blanket is formed of a resilient material,the inherent resiliency of the sealing bead 103 urges it against theglass pane to provide the desired seal.

With the printing frame 25 in a loading condition as shown in FIG. 11,the glass frame 85 being in the elevated position shown in phantom inFIG. 11, a sensitized metal plate 105 (FIG. 15) is laid on the blanket101 thereby to be supported by the protuberances 102. The sensitizedsurface of the plate faces up at this time and a negative 106 to becopied is placed on top of the plate 105, in the manner shown in FIG.15. The glass frame 85 is then lowered by merely pulling it down so asto cause the roller 91 to roll along the guide rail 92 until the frameis in the full line position shown in FIG. 11 wherein the latch 96automatically engages the part 97 to compress the sealing bead 103 andhold the frame 85 in a closed position. A suitable vacuum control switch107 (FIG. 1) located on a control panel 108 at the top front of thecabinet 21 is then actuated to energize the vacuum pump 34 which draws avacuum between the glass pane 86 and the blanket 101 whereby, as bestshown in FIG. 15, the resilient blanket 101 is forced by atmosphericpressure toward the glass pane 86 thereby to firmly press the plate 105and the negative 106 together and against the inner face of the glasspane 86. Accordingly, relative movement between the plate 105 and thenegative 106 is prevented, and more importantly, no air pockets areprovided between the two which would, of course, result in distortion ofthe image projected on the sensitized surface of the plate 105.

In order to connect the vacuum pump 34 to the cavity between the glasspane 86 and the blanket 101, the pintle 84 is tubular and a connectingtube 114 extends into it. The outside end of the tube 114 is connectedto the vacuum pump by means of a flexible conduit 116 and the inside endof the tube 114 is connected to a T junction 118. The T junction 118 isdisposed within the frame 25 and the two outlets thereof are connectedthrough a pair of respective flexible conduits 119 and 120 to a pair ofelbow connectors 121 and 122. The connectors 121 and 122 are tightlyfitted in suitable apertures 124 and 125 provided in the blanket 101.Accordingly, the pump 34 draws air from the space between the blanket101 and the glass pane 86. A pair of enlarged apertures 127 and 128 areprovided in the bottom member 79 in the vicinity of the apertures 124and 125 to provide a large area connection between the back side of theblanket 101 and the atmosphere so that when a vacuum is drawn betweenthe blanket 101 and the glass pane 86, atmospheric pressure is coupledthrough the enlarged apertures 127 and 128 to the back side of theblanket 101 to press it firmly against the glass pane 86.

In order to lock the printing frame 25 in an exposure position with theglass pane 86 facing toward the light source 22, there is provided aspring-loaded manually operable latch 142 (FIG. 5) including aplunger-type bolt 143 which is biased by a spring 147 into an aperturein a latching member 144. The member 144 is attached to the front wall80 of the printing frame 25,

and in order to release the printing frame 25 for rotation thereof tothe loading position, a knob 145 which is threadedly attached to thebolt 143 is pulled out to withdraw the bolt 143 from the aperture in themember 144 and thereby to release the frame 25. A similar latchingmember 144 may be provided on the opposite side of the printing frame 25so that the latch 142 may also be used to lock the frame 25 in theinverted, loading position.

The control panel 108 is mounted on the top of a forwardly extendinglouvered air inlet member 130 which extends along the front of the uppercabinet portion 32 for supplying air through a plurality of apertures131 in the forward wall of the upper cabinet portion 32 into the spacebetween the light source 22 and the printing frame 25. An exhaust fan orblower 132 is mounted over a large aperture 133 in the back wall of theupper cabinet portion 32 for drawing heat and carbon smoke out of thecabinet 21 during operation of the printer. A plurality of angulatedbaflles 134 are respectively mounted above the apertures 131 to deflectthe air which is drawn into the cabinet through the louvred portion ofthe member 130 away from the printing frame 25. A baflie 135 is mounteddirectly above the air outlet aperture 133 for the same purpose.

As indicated hereinbefore, the control panel 108 includes a vacuum pumpcontrol switch 107 and it further includes a vacuum pressure gauge 136and a vacuum adjustment control 137. In addition, a light source controlswitch 138, a timer control adjustment 139, a blower control adjustment140, a master control switch 141 and a vacuum release are provided onthe panel 108 in easy reach ofa person operating the machine.

There is thus provided in accordance with the present invention aphotographic printer 20 which may be used by relatively untrainedpersonnel for making accurate exposures of sensitized metal plates ofthe type used in the photoengraving of onset printing plates. Moreover,the printer 29 is easy to maintain inasmuch as all operating parts arereadily accessible and those parts which must be replaced, i.e., thecarbon electrodes 41 and 42 may be readily removed from the cabinet inorder to make the changing operation extremely simple. Moreover, the ashtray 56 can also be easily removed from the cabinet 21 for cleaning andthe other operating parts of the machine such, for example, as thevacuum pump 34 and drive motor, are readily accessible.

While there has been shown and described a particular embodiment of thepresent invention, it will be apparent to those skilled in the art thatvarious changes and modifications may be made without departing from theinvention in its broader aspects, and it is, therefore, contemplated inthe appended claims to cover all such changes and modifications as fallwithin the true spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. A printer for use in making photographic plates and the like,comprising a cabinet, a source of printing light mounted in the lowerpart of said cabinet for directing light toward the top of said cabinet,a printing frame, mounting means for mounting said frame in the top ofsaid cabinet for pivotal movement about a central axis of said framethereby to permit the positioning of said frame with either side thereoffacing toward said light source, a pump mounted in said cabinet,pressure responsive means disposed in said frame for fixedly positioninga photographic plate or the like in said frame, an apertured pintleincluded in said mounting means for said frame, and a fluid connectionbetween said pump and said pressure responsive means, said connectionincluding the aperture in said pintle.

2. A printer for use in making photographic plates and the like,comprising a cabinet, a source of light mounted in the lower part ofsaid cabinet, a printing frame including a glass plate and animperforate resilient blanket disposed in face-to-face relationship withsaid ,plate having a continuous seal interposed between a peripheralportion of said plate and said blanket, means for drawing a vacuumbetween said blanket and said plate, and mounting means for mountingsaid frame in the top of said cabinet for pivotal movement about acentral axis of said frame thereby to permit the positioning of saidframe with either side thereto facing toward said light source whilemaintaining said vacuum.

3. A photographic printer comprising a cabinet having side Walls formingan interior cavity and defining an upper opening, said openingcommunicating with said cavity and having a given configuration, lightsource and reflector means disposed in the lower end of said cavity forsupplying light upwardly through said upper opening, a generallyuniplanar printing frame of said given configuration disposed in andsubstantially closing said upper opening to provide the top of saidcabinet, said printing frame including both a transparent plate on oneside hinged at one end to said printing frame and holding means forholding a light sensitive sheet adjacent said plate, and mounting meanson said side walls for mounting said printing frame for pivotal movementbetween two positions spaced approximately from each other in which saidframe is effective to substantially close said upper opening, said platebeing disposed below the top of said cabinet in one of said positions toreceive light from said light source and reflector means, said plateforming the top of said cabinet in the other of said positions to permitunobstructed insertion of said sheet spaced from said light source andreflector means.

4. The photographic printer set forth in claim 3 including air inletmeans formed in one of said side walls at a position disposed below saidprinting frame and above said light source and reflector means, saidinlet means providing means for supplying air to said cavity, and motordriven exhaust means mounted on another of said side walls opposite saidone side wall for exhausting air from said cavity.

5. The photographic printer set forth in claim 3 in which said holdingmeans includes a resilient sealing means, and in which said printerincludes a vacuum source in said cavity, and means including saidmounting means for connecting said vacuum source to said resilientsealing means.

References Cited in the file of this patent UNITED STATES PATENTS601,883 Schwarz Apr. 5, 1898 1,167,857 Thorberg Jan. 11, 1916 1,209,419Farquhar Dec. 19, 1916 1,225,729 Fullmer May 8, 1917 1,572,699 WirthweinFeb. 9, 1926 2,229,761 Mueller Jan. 28, 1941 2,713,294 Padgett July 19,1955 2,751,814 Limberger June 26, 1956 2,799,204 Blatherwick July 16,1957

